KR20110106944A - A/d converter and programmable controller system - Google Patents

Abstract

A / D conversion device mounted on a programmable controller (PLC) that converts analog values input from the outside into digital values in order, wherein the log storage area of a ring buffer configuration and next log data for logging the digital values in order A parameter storage area for storing the head pointer which is a parameter indicating the storage location of the data storage device, the digital memory being stored as a log data in a common memory that can be read and accessed from the CPU unit controlling the entire PLC, and at an address indicated by the head pointer of the log storage area. And a logging execution unit for updating the head pointer as well as recording.

Description

A / D converter and programmable controller system {A / D CONVERTER AND PROGRAMMABLE CONTROLLER SYSTEM}

The present invention relates to an A / D converter and a PLC system mounted to a programmable controller (PLC).

When analog data values are input to the PLC, an analog input unit (A / D converter) for converting the input analog data values into digital values is used. In general, the sampling period of the A / D conversion of the analog input unit converting the input analog data value into the digital value and the control period (scan time) of the CPU unit controlling the entire PLC are asynchronous, and the sampling period is high. There are many cases. For this reason, when logging A / D converted values by the analog input unit, it is difficult to log all A / D converted values without failing in the CPU unit.

As a method of logging all A / D conversion values without fail, there is a method of logging processing in the analog input unit, but in order to refer to the collected data, it is necessary to read the data to the CPU unit after completion of logging. . Conventionally, in this read process, it is necessary to execute a dedicated communication process a plurality of times, and there is a problem that it takes time.

Regarding this problem, a technique for storing A / D conversion values in a common memory which is a memory area that is always accessible from a CPU unit without requiring a dedicated communication process has been proposed (see Patent Document 1, for example). . Moreover, as a collection method of continuous data, the technique which collects in a ring buffer form is proposed (for example, refer patent document 2). Moreover, the technique which collects in a ring buffer form to a common memory is proposed (for example, refer patent document 3).

Patent Document 1: Japanese Patent Application Laid-Open No. 8-69355

Patent Document 2: Japanese Patent Application Laid-Open No. 2008-20392

Patent Document 3: Japanese Patent Application Laid-Open No. 2007-233593

However, according to the technique described in Patent Document 1, the previous data is overwritten for every data storage, and continuous data collection and reference are impossible.

Moreover, according to the technique of patent document 2, in the memory area of a ring buffer structure, it was not able to identify the latest and last data, and it was not possible to treat the collected data as time series.

Moreover, the technique described in patent document 3 is for realizing the logging synchronized with the control period of a CPU unit, and it was impossible to log the A / D conversion value updated by the sampling period of a faster A / D conversion.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and it is possible to easily log out all A / D conversion values without fail, and to easily read the logged data without requiring special communication processing in a state capable of matching the time series. It aims to obtain an A / D converter and a PLC system.

In order to achieve the above object, an A / D conversion device mounted on a PLC and converting an analog value input from the outside into a digital value in order, the log storage area of the ring buffer configuration for logging the digital value in order And a parameter storage area for storing a head pointer which is a parameter indicating a storage position of the next log data, the shared memory being read-accessible from a CPU unit controlling the entire PLC; And a logging execution unit for recording the digital value as log data at an address indicated by the head pointer of the log storage area and updating the head pointer.

According to the present invention, a common memory is provided with a parameter storage area for securing a log storage area having a ring buffer structure in the common memory, and for storing a head pointer indicating the boundary address of the latest log data and the oldest log data stored in the log storage area. A / D that can be easily read without logging any A / D conversion value without fail, and requiring no special communication processing in the state that can match the logged data with time series. The effect that a converter can be obtained is achieved.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the PLC system of embodiment which concerns on this invention.
2 is a diagram for explaining a data structure of data stored in a log storage area and a parameter storage area.
3 is a diagram illustrating a data structure of data stored in a log storage area and a parameter storage area.
4 is a flowchart for explaining the operation of the analog input unit according to the embodiment of the present invention.
5 is a flowchart for explaining the operation of the analog input unit according to the embodiment of the present invention.
6 is a diagram illustrating rearrangement of log data.
7 is a view for explaining a log storage area state after rearrangement.

EMBODIMENT OF THE INVENTION Below, with reference to an accompanying drawing, preferable embodiment of the A / D conversion apparatus which concerns on this invention is described in detail. In addition, this invention is not limited by this embodiment.

Embodiment.

1 is a block diagram illustrating a configuration of a PLC system including an A / D converter (analog input unit). As shown, the analog input unit 100 is connected to the CPU unit 200 via the inter-unit bus 300, and the analog input unit 100 and the CPU unit 200 are connected to a part of the PLC 1000. It consists. In addition to the analog input unit 100 and the CPU unit 200, the PLC 1000 controls a servo amplifier or the like according to the purpose to perform a multi-axis position control, or a temperature commanded from the CPU unit 200. Although a temperature controller unit or the like for outputting a temperature control signal for heating and cooling to reach a temperature is mounted via the inter-unit bus 300, units other than the analog input unit 100 and the CPU unit 200 are not mentioned here. Do not.

The analog input unit 100 is configured from a sensor that observes various observation values, such as flow rate, pressure, temperature, and the like, for an industrial device to be controlled by the PLC 1000 and outputs them as current values or voltage values. The input of the analog data value is accepted, the input of the received analog data value is converted into a digital value, and the digital value (A / D converted value) is recorded in the common memory 140 provided therein. The CPU unit 200 operates various units included in the PLC 1000 to acquire input values such as execution of a user program, output of execution results, values used by the user program, and the like, which are programs for controlling industrial equipment. Is repeated in a predetermined cycle. The operation of this iteration is called cyclic processing. The CPU unit 200 reads the digital value (A / D converted value) of the observation value from the common memory 140 as part of the operation of acquiring the input value included in the cyclic processing.

The CPU unit 200 includes an arithmetic unit 210 for executing a user program or controlling the entire CPU unit 200, and an internal memory serving as a memory for storing data necessary for the execution of the user program or input / output values of the user program. 220, the bus I / F 230, which is a communication interface for communicating with the analog input unit 100 via the inter-unit bus 300, the setting of the user program and the data state of the internal memory 220. The personal computer I / F 240 and the indicator I / F 250 which are interfaces for connecting a personal computer which are peripheral devices for display, and an indicator, respectively are provided. The computing unit 210, the internal memory 220, and the bus I / F 230 are each connected by an internal bus. In addition, a system including a PLC 1000 and a peripheral device (personal computer and / or indicator) connected to the PLC 1000 is called a PLC system.

Here, the common memory 140 included in the analog input unit 100 will be described. The common memory 140 has an A / D conversion value storage area 141 which is an area for storing the A / D conversion value read out by the cyclic processing by the CPU unit 200. As described above, since the interval (sampling interval) for sampling the analog data value and converting it into the digital value is usually higher than the period of the cyclic processing, the CPU unit 200 causes the A / D converted value storage area 141 to be used. It is difficult to read and log the A / D conversion value recorded in the file without failing. Therefore, in the embodiment of the present invention, the analog input unit 100 can record data at high speed, and the CPU unit 200 can read and access the common memory 140 without executing complicated communication processing. In addition to the A / D conversion value storage area 141, a log storage area 142 which is a storage area for storing A / D conversion values as log data is assumed to be secured. The log data stored in the log storage area 142 is read out to the peripheral device via the inter-unit bus 300 and the CPU unit 200.

The log storage area 142 has a ring buffer configuration. That is, the log storage area 142 records log data in chronological order from the head address. When the recording address of the log data reaches the end, it wraps around and the log data is overwritten from the head address again. Here, the log data record from the start of logging until the wrap-around time is expressed as the first week record, and thereafter, 1 + n (n is the record of the number of wraparound weeks). We shall express. The common memory 140 stores a parameter storage area for storing the number of input data which is a parameter for obtaining a recording position of the latest log data in the first week, and a head pointer which is a pointer indicating the recording position of the latest log data in the second week or later. 143) is further provided. After the second week, the head pointer indicates the recording position of the latest log data, thus indicating the boundary between the latest log data and the oldest log data.

2 and 3 are diagrams illustrating the data structure of the log storage area 142 and the parameter storage area 143. FIG. 2 shows the data structure for the first week and FIG. 3 for the second week. Here, the log storage area 142 has a storage capacity of N words, and one word of log data (A / D conversion value as log data) is recorded each time T passes. As shown in Fig. 2, the first pointer is fixed at 0 when the time nT (n <N) has elapsed since the start of logging, and the value of the head pointer is fixed to 0, and the number of input data is n + 1. In other words, it can be seen that the recording destination of the next data is the position of the head address + (n + 1) word of the log storage area 142. As shown in Fig. 3, since the latest data is recorded at the position of n-N words from the head address at the second week, the head pointer is n + 1-N, and the number of input data is N (fixed). After the third week, the value of the first pointer is mod (n, N) +1.

Returning to FIG. 1, the analog input unit 100 receives an analog data input interface (I / F) 110 that accepts an input of an analog data value, in addition to the common memory 140, and converts the received analog data value into a digital value. A / D conversion unit 120 for converting to (A / D conversion value), trigger input interface (I / F) 150 for accepting a trigger for stopping logging of A / D conversion value, and analog input A computing unit 130 for controlling the entire unit 100 and a bus I / F 160 which is a communication interface for communicating with the CPU unit 200 via the inter-unit bus 300 are provided. The arithmetic unit 130, the common memory 140, and the bus I / F 160 are each connected by an internal bus.

The calculation unit 130 is based on a trigger detector 131 for detecting a trigger received by the trigger input I / F 150, a parameter detected by the trigger and the parameter storage area 143 detected by the trigger detector 131. In addition, a logging execution unit 132 is further provided to record the A / D conversion values output from the A / D conversion unit 120 in the log storage area 142 as log data. The logging execution unit 132 records the log data for a predetermined number of data (the number of data after the trigger) from the time when the trigger detection unit 131 detects the trigger, and then stops logging. As the trigger, in addition to the trigger by the signal input from the trigger input I / F 150, for example, the following various types of triggers can be used.

• Trigger by the internal signal of the PLC 1000.

• Trigger that occurs when the A / D conversion value is larger or smaller than the set value.

• A timing trigger that occurs every hour on the hour using the internal clock information of the PLC 1000.

A buffer pool trigger that occurs when the capacity of the log storage area 142 becomes full.

ㆍ Error trigger and alarm trigger in conjunction with the error output function and alarm detection function provided in the analog input unit 100.

Multiple triggers occurring under a plurality of AND and OR conditions among the triggers.

Next, the operation of the embodiment of the present invention will be described with reference to FIGS. 4 and 5. 4 and 5 are flowcharts for explaining the operation of the analog input unit 100.

In FIG. 4, first, the logging execution unit 132 acquires initial settings relating to logging set by the user (step S10). In the initial setting, the logging cycle, trigger type, and post-trigger data count are set. In the logging cycle, an integer multiple of the sampling interval cycle is set.

Subsequently, the logging execution unit 132 starts the logging operation of the A / D conversion values when the A / D conversion by the A / D conversion unit 120 is started (step S11). Specifically, the logging execution unit 132 determines whether the logging cycle interval time has been reached using a timer or a counter in order to record log data in the log storage area 142 for each logging cycle (step S12).

When the elapsed time from the step S11 or the previous record does not reach the logging cycle interval time (step S12, NO), it is determined whether or not the logging cycle interval time has been reached. When the logging cycle interval time has been reached (step S12, YES), the logging execution unit 132 further determines whether logging is the first week (step S13). Whether or not logging is the first week can be determined by, for example, whether the storage capacity indicated by the value of the input data number is equal to the storage area of the log storage area 142.

When logging is the first week (step S13, YES), the logging execution unit 132 acquires the number of input data from the parameter storage area 143 (step S14), and the A / D conversion unit 120 outputs A. The / D converted value is recorded at an address obtained by adding the capacity of the input data moisture to the head address of the log storage area 142 (step S15). The logging execution unit 132 then updates by adding one input data number (step S16).

If logging is after the second week (step S13, NO), the logging execution unit 132 obtains the head pointer from the parameter storage area 143 (step S17), and the A / D conversion unit 120 outputs A. The / D converted value is written to the address indicated by the head pointer of the log storage area 142 (step S18). The logging execution unit 132 then adds one data portion to the head pointer (step S19), and determines whether the head pointer has passed the last address of the log storage area 142 (step S20). When the last address is exceeded (step S20, YES), the head pointer is set to the head address of the log storage area 142 (step S21).

If the head pointer does not exceed the last address of the log storage area 142 in step S16, step S21 or step S20 (step S20, NO), the logging execution unit 132 stores the number of stored data in the parameter storage area 143. To the parameter storage area 143 (step S23), and the process proceeds to step S12.

Next, the operation of the analog input unit 100 when the trigger is detected will be described. 5 is a diagram illustrating the operation of the analog input unit 100 when a trigger is detected.

First, the logging execution unit 132 acquires the initial setting and acquires the number of post-trigger data (step S30). The logging execution unit 132 then determines whether the trigger detection unit 131 has detected a trigger (step S31). If the trigger is not detected (step S31, NO), the determination is continued until the continuous trigger is detected. If a trigger is detected (step S31, YES), the logging execution unit 132 further determines whether or not data after the trigger has been recorded in the log storage area 142 after detecting the trigger (step S32). ). If data of the data moisture after the trigger is not recorded in the log storage area 142 (step S32, NO), the determination is continued until data of the data moisture after the trigger is recorded.

When data of the data moisture after the trigger is recorded in the log storage area 142 (step S32, YES), the logging execution unit 132 stops the log data storage process (step S33) and starts the head of the log storage area 142. The log data stored in the log storage area 142 is rearranged so as to be in chronological order (step S34). 6 is a view for explaining rearrangement in step S34. As described above, since the log storage area 142 has a ring buffer configuration, as shown in the left figure of FIG. 6, at a predetermined time point, a boundary between the latest log data and the oldest log data exists. The logging execution unit 132 rearranges the data stored as shown in the left side of FIG. 6 as shown in the right side of FIG. 6 so that the oldest log data and the latest log data are stored at the beginning. 7 is a view for explaining the state of the log storage area 142 after rearrangement. As shown in Fig. 7, the log data of the number of post-trigger data is stored in the address after the write address at the time of trigger detection. In this example, the rearrangement is performed in chronological order from the beginning, but may be rearranged so as to be in chronological order from the end.

After step S34, the logging execution unit 132 turns on the logging completion flag indicating that logging has been completed (step S35), and ends the operation. In addition, some bits in the common memory 140 may be used as a storage area for logging completion flags, and bits of this storage area may be set to 1 to indicate logging completion, or other storage areas may be set as logging completion flags. good. In addition, the logging execution unit 132 may turn on the logging completion flag and may notify the CPU unit 200 that logging has been completed. In this state, if the personal computer or the displayer reads log data in order from the head address of the log storage area 142, the log data can be obtained in a time series order.

In addition, in step S34, the data is rearranged so that the data is stored in the chronological order from the head address. However, it is possible to configure whether or not the operation of step S34 is performed by the initial setting. In the case of skipping, if the peripheral device reads not only the log data but also the head pointer, it becomes possible to rearrange the log data in chronological order on the peripheral device side. In addition, the peripheral device may read and access the common memory 140 at any time, as well as when the logging completion flag is turned on, to read log data. In that case, the head pointer may also be read as described above.

In addition, although explanation was given by logging at a sampling processing interval earlier than the cycle of the cyclic processing, the logging cycle is set later than the cycle of the cyclic processing, and the log data is read out to the peripheral device in near real time through the CPU unit 200. You may do so. In addition, when the peripheral device arranges the read log data in the order of reading, the real time trend graph showing the temporal trend of the log data can be created.

As described above, according to the embodiment of the present invention, the analog input unit 100 secures the log storage area 142 of the ring buffer structure in the common memory 140 and logs stored in the log storage area 142. Since the head pointer indicating the boundary address of the latest log data and the oldest log data among the data is stored in the common memory 140, all A / D conversion values are logged without fail, and the logged data is stored in time series and In a compatible state, it can be easily read without requiring special communication processing. In addition, since the analog input unit 100 is configured to rearrange the log data stored in the log storage area 142 having a ring buffer configuration in chronological order, log data in chronological order is not executed. You can read it.

In the above description, the A / D converted value read out by the cyclic processing is stored in the A / D converted value storage area 141, and the log data of the A / D converted value is stored in the log storage area 142. Although it demonstrated as mentioned above, the A / D conversion value storage area | region 141 is deleted, and the CPU unit 200 uses the A / D conversion value as log data stored in the log storage area | region 142 in a cyclic process. You may read it. At that time, the CPU 200 may refer to the storage position of the latest data based on the head pointer or the number of input data. That is, in the first week, the address obtained by adding the storage capacity of the input data moisture to the head address becomes an address in which the latest A / D conversion value is stored, and in the second week or later, the first pointer-1 This address becomes the address where the latest A / D conversion value is stored. In addition, when the user program uses the past value of the A / D converted value, the CPU unit 200 may read the past value of the A / D converted value stored as log data in the log storage area 142. .

In addition, after the logging is stopped by trigger detection, the trigger condition may be released to resume the logging process. As a result, the start and stop of logging can be controlled by turning on and off the trigger condition.

In addition, although A / D conversion part 120 starts logging when A / D conversion starts, you may start logging by trigger detection after A / D conversion start.

[Industrial availability]

As described above, the A / D converter and the PLC system according to the present invention are very suitable for application to the A / D converter and the PLC system mounted on the PLC.

100 analog input units
110 analog data input I / F
120 A / D Converter
130 calculator
131 trigger detector
132 Logging Execution Unit
140 common memory
141 A / D conversion value storage area
142 Log Containment Area
143 Parameter Storage Area
150 trigger input I / F
160 bus I / F
210 calculator
220 internal memory
230 bus I / F
240 personal computer I / F
250 indicator I / F
300 inter-unit buses
1000 PLC

Claims (5)

In the A / D conversion device mounted on a programmable controller (PLC), converting analog values input from the outside into digital values in order,
A CPU unit having a log storage area of a ring buffer configuration for logging the digital values in order and a parameter storage area for storing a head pointer which is a parameter indicating a storage position of the next log data, and the CPU unit controlling the entire PLC; Shared memory that can be read from, and
And a logging execution unit for recording a digital value as log data at an address indicated by the head pointer of the log storage area and updating the head pointer. The method according to claim 1,
And the logging execution unit stops logging, and changes the storage position of each log data stored in the log storage area based on the head pointer and arranges them in chronological order. The method according to claim 2,
And the logging execution unit stops logging when a predetermined trigger detects a predetermined trigger, when the number of log data logged after a point in time when the trigger is detected reaches a predetermined predetermined number. The method according to claim 3,
The predetermined trigger includes an internal signal of the PLC, an input signal input from the outside, a signal generated when an A / D conversion value is smaller or larger than a predetermined value, a timing signal using the internal clock information of the PLC, and the log. Receive all or a plurality of signals from the group consisting of a buffer full signal to stop logging when the storage area becomes empty, an alarm issued by the user, or a signal issued by the user when an error is detected. Or a signal generated when one signal is received. A PLC having an A / D conversion device according to any one of claims 1 to 4, a CPU unit, and a bus that connects the A / D conversion device and the CPU unit, and through the CPU unit and the bus, A programmable controller system having a peripheral device for reading log data from a log storage area of a common memory included in an A / D converter,
And the peripheral device reads the log data in near real time and displays a trend graph in which the digital values of the read log data are arranged in chronological order.

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